RDMA/hns: Update the usage of ack timeout in hip08

The ack timeout's value in qp context shall be a 5-bit value
and be assgined by users. When at of qpc is set zero, the
timer is disabled.

When attr_mask set for IB_QP_TIMEOUT, The ack timeout field
is effective.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Shaobo Xu <xushaobo2@huawei.com>
Signed-off-by: Yixian Liu <liuyixian@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>